I was doing a math problem this morning and realized that the solution lied in the fact that if a function of A -> A is one to one then it is onto. It is so obvious that I have been taking it for granted for so long time.(adsbygoogle = window.adsbygoogle || []).push({});

But now when I think of it deeply, I find it very interesting and relating to some foundational questions like set theory and relation.

Hope you can join with me working on this.

**Physics Forums | Science Articles, Homework Help, Discussion**

Join Physics Forums Today!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

# How to prove a one to one function A -> A is also a onto function?

**Physics Forums | Science Articles, Homework Help, Discussion**